Skip to main content

Consuming a REST Web Service returning JSON in APEX

In APEX you can define a web service that returns XML as below - all declarative, just a few steps through a wizard.


Then generate a report on top of that web service - again just a few clicks through a wizard. The generated query looks like this:

select xtab."customerName"
     , xtab."customerId"
  from apex_collections c, 
          XMLTable('/Response/S_getCustomerListTableArray/S_getCustomerListArrayItem' passing xmltype001
            COLUMNS "customerName" PATH 'customerName'
                  , "customerId"   PATH 'customerId'
          ) xtab
 where c.collection_name = 'CUSTOMERLIST'

So the result of the web service is stored in an XMLTYPE column. And it's easy to spot where you're definitions for the Response XPath and Output Parameters are used.

But what if your web service returns JSON - as more and more web services will do so? If you switch the Output Format of the web service definition to JSON, the Response XPath property and the Output Parameters are not enterable. And if you generate a report on top of that web service, the resulting query is a - disappointing - 

select c.clob001
from apex_collections c
where c.collection_name = 'CUSTOMERLIST'

and your report will show a JSON dump. Not exactly what you're hoping for. And notice the result is stored in a CLOB.

But since 12c, the JSON support in the Oracle database has improved a lot and we can easily use that in our query. So if we rewrite our query to 

select cust.*
from   apex_collections
,      json_table(clob001, '$.Response.S_getCustomerListTableArray.S_getCustomerListArrayItem[*]'
       columns ( "customerName"   PATH '$.customerName'
               , "customerId"     PATH '$.customerId'
               )) cust
where collection_name = 'CUSTOMERLIST'

we will get the same result as the - old fashioned - XML one! And as you can see the code is very much alike and could be generated by APEX itself just like the XML version.

So I expect that in a future version this functionality will be added to the APEX builder - it shouldn't be that hard to implement! And maybe the apex_collections can have a real "JSON" column as well (in fact it would still be a CLOB with an "IS JSON" check).

The only prerequisite is, you have to run APEX on version 12c of the database. If you want to know more about JSON in the database, there is a serie of blog posts about this, starting here.

Comments

Popular posts from this blog

Using Static Files in APEX has never been easier !

Almost every APEX Developer knows that JavaScript and CSS belongs in separate files and (in 99% of the use cases) not somewhere in your Page properties. If you have this code in separate files it is easier to use them in a Version Control System (SVN or Git) - if the files are outside of APEX. And the code you store in these files can be reused, in contrast to the stuff you store on Page level. In a lot of environments it is harder to use external files, because deployment of these files to the appropriate location on a webserver requires special privileges that not everybody has. In those cases storing these files as Static Application Files or Static Workspace Files might be a better solution. It makes deployment easier, because these files will be exported and imported as part of the application. You can't accidentally forget about them. But working with these files is quite a pain. When you need to edit something you have to download that file, make the changes, upload it again

Filtering in the APEX Interactive Grid

Remember Oracle Forms? One of the nice features of Forms was the use of GLOBAL items. More or less comparable to Application Items in APEX. These GLOBALS where often used to pre-query data. For example you queried Employee 200 in Form A, then opened Form B and on opening that Form the Employee field is filled with that (GLOBAL) value of 200 and the query was executed. So without additional keys strokes or entering data, when switching to another Form a user would immediately see the data in the same context. And they loved that. In APEX you can create a similar experience using Application Items (or an Item on the Global Page) for Classic Reports (by setting a Default Value to a Search Item) and Interactive Reports (using the  APEX_IR.ADD_FILTER  procedure). But what about the Interactive Grid? There is no APEX_IG package ... so the first thing we have to figure out is how can we set a filter programmatically? Start with creating an Interactive Grid based upon the good old Employ

Adding items to your Interactive Grid Toolbar

The APEX Interactive Grid uses the Toolbar widget to create the default Toolbar showing the Search box, Actions menu, Save button etc. And since quite a while there is a nice Plugin " Extend IG Toolbar " by Marko Goricki that makes it very easy to add additional buttons to the Toolbar. But what if you need more than a button?  Inspecting the contents of widget.toolbar.js, you can easily spot there can be added more to the Toolbar than just a button: The type of control, available values: "STATIC", "TEXT", "SELECT", "BUTTON", "MENU", "RADIO_GROUP", "TOGGLE". The first example will show a way to easily switch from one filter to another. Of course we could use the standard functionality and create two different Report views, but using a Radio Group on the Toolbar gives a more "Tab" like user experience. So how can we create a Radio Group that looks like a switch in the Toolbar? In